fix: protected branch detection and non-blocking hooks

- Add protected branch detection to /commit command (Step 1)
- Warn users before committing to protected branches
- Offer to create feature branch automatically
- Rewrite doc-guardian hook to be truly non-blocking
- Enforce strict [plugin-name] prefix in all hook outputs
- Add forbidden words list to prevent accidental blocking

Fixes #109, #110

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/pr-review/hooks/hooks.json

@@ -3,7 +3,7 @@
     "SessionStart": [
       {
         "type": "prompt",
-        "prompt": "[pr-review] Perform silent startup checks:\n\n1. Check if MCP venvs exist at the installed marketplace location. If the marketplace is installed but venvs are missing, warn the user: '[pr-review] MCP venvs missing - run setup.sh from installed marketplace location'.\n\n2. Check if the project git remote matches .env configuration (GITEA_ORG/GITEA_REPO). If mismatch, warn: '[pr-review] Git remote mismatch - run /project-sync'.\n\nStay silent if all checks pass or not applicable. Be quick and non-blocking."
+        "prompt": "STARTUP CHECK - STRICT OUTPUT FORMAT:\n\nALL outputs MUST start with '[pr-review]' - NO EXCEPTIONS.\n\nPerform quick silent checks:\n1. If MCP venvs missing: '[pr-review] MCP venvs missing - run setup.sh from installed marketplace'\n2. If git remote != .env config: '[pr-review] Git remote mismatch - run /pr-review:project-sync'\n\nIf all checks pass: Say nothing (empty response)\n\nRules:\n- NEVER output without '[pr-review]' prefix\n- Keep messages under 20 words\n- Be quick and non-blocking\n- Do not read files or perform deep analysis"
       }
     ]
   }